Method to manufacture magnetic tunneling elements using inductively coupled plasma

Abstract

A magnetic tunneling element in which the tunnel current flows reliably to exhibit a stable magnetic tunneling effect. The magnetic tunneling element includes a first magnetic layer, a tunnel barrier layer formed on the first magnetic layer, and a second magnetic layer formed on the tunnel barrier layer. The tunnel barrier layer is a metal film oxidized by inductively coupled oxygen plasma and a second magnetic layer is formed on the tunnel barrier layer.

What is claimed is:  
     
       1. A method for manufacturing a magnetic tunnelling element comprising: 
       forming a first magnetic layer, wherein the first magnetic layer includes a first Co layer and a free magnetization layer, wherein direction of the magnetization of the free magnetization layer is susceptible to change in response to an external magnetic field;  
       forming a tunnel barrier layer on the first magnetic layer by oxidizing a metal film through inductively coupled Ar/oxygen plasma from a mixed atmosphere of Ar/oxygen gas; and  
       forming a second magnetic layer over the first magnetic layer, wherein the second magnetic layer includes a pinned magnetization layer positioned against a second Co layer so as to fix a direction of magnetization of the second Co layer in a predetermined direction and wherein the tunnel barrier layer is positioned between the first Co layer and the second Co layer;  
       wherein the step of oxidizing the metal film includes supplying the Ar/oxygen gas at a flow rate of Ar/O 2 =10/30 sccm and a pressure of 1 Pa and further includes applying 200 W of power to a coil.  
     
     
       2. The method of  claim 1 , wherein the free magnetization layer is a NiFe layer and the ratio of a thickness of the NiFe layer to the first Co layer is approximately 5 to 1. 
     
     
       3. The method of  claim 2 , wherein the pinned magnetization layer is an IrMn layer and the ratio of a thickness of the IrMn layer to the second Co layer is approximately 3 to 1. 
     
     
       4. The method of  claim 3 , wherein the ratio of the thickness of the NiFe layer to the first Co layer is 18.8 to 3.9, wherein the ratio of a thickness of the IrMn layer to the second Co layer is 15 to 5, and wherein the tunnel barrier layer includes an oxidized Al film having a thickness of 1.3 nm. 
     
     
       5. The method of  claim 2 , wherein the pinned magnetization layer includes a NiFe layer and a FeMn layer and wherein the second magnetic layer further includes a Ta layer to prohibit corrosion. 
     
     
       6. The method of  claim 5 , wherein the ratio of a thickness of the second Co layer to the NiFe layer, the FeMn layer, and the Ta layer is approximately 1 to 9 to 23 to 10. 
     
     
       7. The method of  claim 6 , wherein the thickness of the second Co layer is 2.6 nm, the thickness of the NiFe layer is 18.8 nm, the thickness of the FeMn layer is 45, and the thickness of the Ta layer is 20 nm. 
     
     
       8. A method for manufacturing a magnetic tunnelling element comprising: 
       forming a first magnetic layer, wherein the first magnetic layer includes a first Co layer and a free magnetization layer, wherein direction of the magnetization of the free magnetization layer is susceptible to change in response to an external magnetic field;  
       forming a tunnel barrier layer on the first magnetic layer by oxidizing a metal film through inductively coupled Ar/oxygen plasma from a mixed atmosphere of Ar/oxygen gas; and  
       forming a second magnetic layer over the first magnetic layer, wherein the second magnetic layer includes a pinned magnetization layer positioned against a second Co layer so as to fix a direction of magnetization of the second Co layer in a predetermined direction and wherein the tunnel barrier layer is positioned between the first Co layer and the second Co layer;  
       wherein the step of oxidizing the metal film includes supplying the Ar/oxygen gas at a flow rate of Ar/O 2 =40/4 sccm and a pressure of 0.3 Pa and further includes applying 20 W of power to a coil and setting the reaction time to 1000 seconds.  
     
     
       9. The method of  claim 8 , wherein the free magnetization layer is a NiFe layer and the ratio of a thickness of the NiFe layer to the first Co layer is approximately 5 to 1. 
     
     
       10. The method of  claim 9 , wherein the pinned magnetization layer includes a NiFe layer and a FeMn layer and wherein the second magnetic layer further includes a Ta layer to prohibit corrosion. 
     
     
       11. The method of  claim 10 , wherein the ratio of a thickness of the second Co layer to the NiFe layer, the FeMn layer, and the Ta layer is approximately 1 to 9 to 23 to 10. 
     
     
       12. The method of  claim 11 , wherein the thickness of the second Co layer is 2.6 nm, the thickness of the NiFe layer is 18.8 nm, the thickness of the FeMn layer is 45, and the thickness of the Ta layer is 20 nm.